Heater for manufacturing a crystal

ABSTRACT

The present invention provides a heater for manufacturing a crystal by the Czochralski method comprising at least terminal portions supplied with current and a heat generating portion by resistance heating, and being arranged so as to surround a crucible containing a raw material melt, wherein the heater has a uniform heat generation distribution to the raw material melt after deformation while in use during crystal manufacture. It is thus possible to prevent hindrance of monocrystallization and unstable crystal quality caused by ununiform temperature in the raw material melt due to deformation of the shape of the heater&#39;s heat generating portion while in use during crystal manufacture.

TECHNICAL FIELD

The present invention relates to a heater for manufacturing a crystalused during crystal growth by the Czochralski method, a crystalmanufacturing apparatus and a crystal manufacturing method using theheater and more particularly to a heater for manufacturing a crystalsuited to manufacturing large diameter crystals of eight inches or morein diameter while applying a magnetic field, a crystal manufacturingapparatus and a crystal manufacturing method using the heater.

BACKGROUND ART

Silicon single crystal, one of the crystals used as semiconductor devicesubstrates, is primarily manufactured by the Czochralski method(hereinafter abbreviated as “CZ method”).

When crystals are manufactured by the CZ method, a crystal manufacturingapparatus as shown in FIG. 4 is, for example, used. The manufacturingapparatus has, for example, members for melting a raw materialpolycrystal such as silicon and a mechanism for pulling monocrystallizedsilicon, and these members and the mechanism are accommodated in a mainchamber 11. A pulling chamber 12 extending upward is connected from aceiling portion of the main chamber 11, with a mechanism (not shown)provided on top thereof for pulling a crystal 4 with a wire 10.

Within the main chamber 11, a crucible 5 is arranged for containing amelted raw material melt 6, with the crucible 5 supported by a shaft 9so as to be free to rotate and move up and down with a drive mechanism(not shown). To compensate for decline in melt level as a result ofpulling of the crystal 4, the drive mechanism for the crucible 5 isdesigned to raise the crucible 5 as much as the melt level declines.

A heater 7 for melting raw material is arranged so as to surround thecrucible 5. A heat-insulating material 8 is provided outside the heater7 so as to encircle the heater 7, thus preventing direct radiation ofheat from the heater 7 to the main chamber 11.

A lump of raw material is accommodated in the crucible 5 arranged withinsuch a crystal manufacturing apparatus followed by heating of thecrucible 5 with the heater 7, thus melting the lump of raw material inthe crucible 5. The crystal 4 of a desired diameter and quality is grownbelow a seed crystal 2, fastened with a seed holder 1 connected to thewire 10, by allowing the seed crystal 2 to be immersed into the rawmaterial melt 6 resulting from melting of the lump of raw material andthen pulling the seed crystal 2. At this time, so-called “necking” isperformed in which a neck portion 3 is formed by narrowing the diameterto roughly 3 mm after the seed crystal 2 is immersed into the rawmaterial melt 6, followed by thickening of a crystal until a desireddiameter is reached and then pulling of the dislocation free crystal.

The so-called MCZ method (Magnetic field applied Czochralski Method), animproved version of the CZ method, is also known recently. With the MCZmethod, a magnetic field is applied to a raw material melt, suppressingthermal convection of the raw material melt and thus manufacturing acrystal. While large diameter silicon single crystals of eight inches ormore in diameter are recently in demand, the MCZ method capable ofsuppressing thermal convection of the raw material melt is effective formanufacturing such large diameter silicon single crystals.

Here, the heater 7 for manufacturing a crystal used in theaforementioned CZ and MCZ methods is cylindrical shape as shown in FIG.1 and primarily made of isotropic graphite. In the direct current type,currently in vogue, two terminal portions 7 b are provided, with theheater 7 supported by the terminal portions 7 b. A heat generatingportion 7 a of the heater 7 has slits 7 c provided at several to severaltens of locations for efficient heat generation. It is to be noted thatthe heater 7 generates heat mainly from individual heat-generating slitportions 7 d—the portions between the lower end of slits extending fromthe top and the upper end of slits extending from the bottom.

The crucible must be naturally used larger in size to manufacture largediameter crystals in demand recently at low cost. As a result ofupsizing of the crucible, structures around the crucible such as theheater have been upsized. Upsizing of the heater has led to problems todeformation of the heater while in use for crystal manufacture due toheater's own weight and ununiform heat distribution, and further becauseof interaction between magnetic field and current in the case ofmagnetic field application as in the MCZ method. Deformation of theheater while in use in crystal manufacture changes the distance betweenthe heater's heat-generating portion and the crystal ingot or the melt,thus changing the heat distribution. This in turn gives rise toununiform temperature within the raw material melt, resulting indetrimental effects such as hindrance of monocrystallization of thecrystal manufactured and unstable quality.

As a countermeasure thereof, dummy terminals are commonly attached tothe heater in addition to the two terminal portions, thus supporting theheater by three or more portions (e.g., Japanese Patent Publication No.7-72116). If the heater is supported by the terminal portions alone, itis supported only at two locations, resulting in easy deformation atthose portions with no terminals. This deformation takes place at theupper portion of the heater in such a manner that those portions withterminals expand in diameter while those portions without terminalsdiminish in diameter. Providing dummy terminals at the portions with noterminals has been effective to a certain extent to prevent such aheater deformation.

However, the heater is divided by slits, making it impossible tocompletely prevent deformation by provision of terminals and dummyterminals alone. In the case of a larger diameter or taller heater inparticular, it is difficult to suppress deformation. In addition to theabove, this method led to other problems such as heat loss from thedummy terminal portions and further more complex mechanicalconstruction.

Further, in the MCZ method for manufacturing large diameter crystalswhile applying a current magnetic field, deformation is caused not onlyby heater's own weight and thermal expansion but also electromagneticforce resulting from interaction between heater current and magneticfield. This electromagnetic force is considerably strong, making itdifficult to avoid heater deformation even if the heater is supported bythe entire lower end.

Accordingly, a method is proposed in the MCZ method that preventsdeformation by using a doubled-structured heater consisting of slittedinner and outer heaters and apply direct currents in differentdirections in respectively, thus suppressing electromagnetic forceresulting from interaction between heater current and magnetic field(e.g., Japanese Patent Application Laid-Open Publication No. 9-208371).The aforementioned method, although being effective to a certain extentfor preventing deformation due to electromagnetic force, results inproblems such as considerably increased cost due to more complexmechanical construction and larger deformation, conversely, due toheater's own weight.

Meanwhile, an attempt is being tried out to change the heater materialfrom isotropic graphite to a stronger and lighter material such ascarbon composite. However, this method leads to problems such asunstable heat generation, higher heater material cost and further lowerpurity of crystal manufactured.

DISCLOSURE OF THE INVENTION

In light of the above problems, it is an object of the present inventionto provide a heater for manufacturing a crystal, a crystal manufacturingapparatus and a crystal manufacturing method using the heater capable ofinexpensively, easily and reliably preventing hindrance ofmonocrystallization and unstable crystal quality caused by ununiformtemperature in the raw material melt due to deformation of the shape ofthe heater's heat generating portion while in use for crystalmanufacture even in the case of manufacture of large diameter crystalsof eight inches or more in diameter.

The present invention was conceived to solve the above problems.According to the present invention, there is provided a heater formanufacturing a crystal by the Czochralski method comprising at leastterminal portions supplied with current and a heat generating portion byresistance heating, and being arranged so as to surround a cruciblecontaining a raw material melt, wherein the heater has a uniform heatgeneration distribution to the raw material melt after the heater shapeundergoes deformation while in use during crystal manufacture.

Thus, the heater has a uniform heat generation distribution to the rawmaterial melt after the heater shape undergoes deformation while in useduring crystal manufacture, making it possible to reduce temperaturegradient in the raw material melt following deformation. This suppressesthe crystal from becoming dislocated during pulling, allowing obtainingcrystals of high quality in an inexpensive, easy and reliable manner.

It is to be noted that the term “uniform heat generation distribution tothe raw material melt” indicates that heat from the heater is radiatedconcentrically toward the raw material melt.

According to the present invention, there is provided a heater formanufacturing a crystal by the Czochralski method comprising at leastterminal portions supplied with current and a heat generating portion byresistance heating, and being arranged so as to surround a cruciblecontaining a raw material melt, wherein a shape of a horizontal crosssection of the heat generating portion of the heater is an ellipticalshape, and the shape of the horizontal cross section of the heatgenerating portion becomes a circular shape as a result of heater shapedeformation while in use during crystal manufacture.

Thus, the heater's heat generating portion is elliptical in horizontalcross section but becomes circular in horizontal cross section as aresult of heater deformation while in use during crystal manufacture,making it possible to provide a uniform heat generation distribution tothe raw material melt after deformation. This suppresses the crystalfrom becoming dislocated during pulling, allowing obtaining crystals ofhigh quality in an inexpensive, easy and reliable manner.

In this case, the elliptical shape of the horizontal cross section ofthe heat generating portion is preferably achieved by reducing thediameter in advance in the direction in which the diameter grows largeras a result of heater shape deformation while in use during crystalmanufacture and by expanding the diameter in advance in the direction inwhich the diameter grows smaller. When, in the elliptical shape of thehorizontal cross section of the heat generating portion, the longerdiameter is D1 and the shorter diameter is D2, the value of D1/D2 ispreferably 1.01 to 1.20.

Thus, the elliptical shape of the horizontal cross section of the heatgenerating portion is achieved by reducing the diameter in advance inthe direction in which the diameter grows larger as a result of heatershape deformation while in use during crystal manufacture and byexpanding the diameter in advance in the direction in which the diametergrows smaller, making it possible to reliably provide uniform heatgeneration to the raw material melt after deformation. It is preferredin terms of heater machinability, cost and strength that the ratio ofthe longer diameter to the shorter diameter of the elliptical shape be1.01 to 1.20.

The present invention further provides a heater for manufacturing acrystal by the Czochralski method comprising at least terminal portionssupplied with current and a heat generating portion by resistanceheating, and being arranged so as to surround a crucible containing araw material melt, wherein the heat generating portion of the heater hasan uneven distribution of electrical resistance.

Thus, the heater's heat generating portion has an uneven distribution ofelectrical resistance, making it possible to provide uniform heatgeneration to the raw material melt after deformation. This suppressesthe crystal from becoming dislocated during pulling, allowing obtainingcrystals of high quality in an inexpensive, easy and reliable manner.

In this case, the uneven distribution of electrical resistance of theheat generating portion is preferably such that electrical resistance isincreased in advance in the direction in which the diameter grows largeras a result of heater shape deformation while in use during crystalmanufacture, whereas electrical resistance is reduced in advance in thedirection in which the diameter grows smaller.

Thus, the uneven distribution of electrical resistance of the heatgenerating portion is such that electrical resistance is increased inadvance in the direction in which the diameter grows larger as a resultof heater shape deformation while in use during crystal manufacture,whereas electrical resistance is reduced in advance in the direction inwhich the diameter grows smaller, making it possible to provide auniform heat generation distribution to the raw material melt afterdeformation.

In this case, the uneven distribution of electrical resistance of theheat generating portion is preferably adjusted by changing one or moreof thickness, width, and length of heat generating slit portions.

Thus, the uneven distribution of electrical resistance of the heatgenerating portion can be readily adjusted by changing one or more ofthe heat generating slit portions' thickness, width and length.

The uneven distribution of electrical resistance of the heat generatingportion is preferably such that when electrical resistance is R1 in thedirection in which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and electricalresistance is R2 in the direction in which the diameter grows smaller,the value of R1/R2 is 1.01 to 1.10.

Thus, the uneven distribution of electrical resistance of the heatgenerating portion is such that when electrical resistance is R1 in thedirection in which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and electricalresistance is R2 in the direction in which the diameter grows smaller,the value of R1/R2 is 1.01 to 1.10, making it possible to reliablyprovide uniform heat generation to the raw material melt afterdeformation without bringing about serious problems in terms of heatermachining, strength and others.

In the heater for manufacturing a crystal of the present invention, theshape of the horizontal cross section of the heat generating portion ofthe heater may be an elliptical shape, and the shape of the horizontalcross section of the heat generating portion may become a circular shapeas a result of heater shape deformation while in use during crystalmanufacture. In addition, the heat generating portion of the heater mayhave the uneven distribution of electrical resistance.

Thus, in addition to the fact that the heater's heat generating portionis elliptical in horizontal cross section but becomes circular inhorizontal cross section as a result of heater shape deformation whilein use during crystal manufacture, the heat generating portion has theuneven distribution of electrical resistance, making it possible tominutely and finely adjust heat generation to the raw material meltafter deformation and thereby reliably providing a uniform heatgeneration distribution.

Further, the Czochralski method in which the heater is used may be theMCZ method.

Thus, the heater for manufacturing a crystal according to the presentinvention is particularly effective for manufacturing a crystal by theMCZ method. The reason for this lies in that the MCZ method isparticularly employed for manufacturing large diameter crystals and thatthe heater more readily deforms as a result of interaction betweencurrent and magnetic field.

Further, the crystal to be manufactured can be silicon single crystals.

In this manner, the heater for manufacturing a crystal according to thepresent invention can be used as a heater for manufacturing siliconsingle crystals that have seen significant growth in diameter andupsizing of the heater as a result thereof particularly recently.

Further, the present invention provides a crystal manufacturingapparatus comprising the aforementioned heater for manufacturing acrystal and a crystal manufacturing method for manufacturing a crystalby the Czochralski method using the crystal manufacturing apparatus.

It is possible to obtain crystals of high quality in an inexpensive,easy and reliable manner by manufacturing a crystal by the Czochralskimethod using the crystal manufacturing apparatus furnished with theheater for manufacturing a crystal according to the present invention.

As described above, the heater used for manufacturing a crystal by theCZ method has a uniform heat generation distribution to the raw materialmelt, according to the present invention, after the shape of the heatgenerating portion undergoes a deformation while in use during crystalmanufacture, providing improved dislocation free rate of crystals insingle crystal manufacture and thereby reliably ensuring stablemanufacture of high-quality crystals in an inexpensive, easy andreliable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view showing a heater formanufacturing a crystal;

FIGS. 2( a) and 2(b) are schematic views respectively showing thehorizontal cross-sectional shape of a heat generating portion of theelliptical heater for manufacturing a crystal according to the presentinvention before and after deformation;

FIGS. 3( a) and 3(b) are schematic views respectively showing thehorizontal cross-sectional shape of a heat generating portion of aconventional circular heater for manufacturing a crystal before andafter deformation; and

FIG. 4 is a schematic view showing a crystal manufacturing apparatus bythe CZ method.

BEST MODE FOR CARRYING OUT THE INVENTION

While examples of the present invention will be described below, thepresent invention is not limited thereto.

In today's large diameter crystal manufacturing using large-sizedheater, in particular, it is difficult to completely prevent heatershape deformation while in use during crystal manufacture. While theheater may be divided to prevent such a heater shape deformation, thedivision would likely lead to problems such as more complex innerconstruction of the furnace and higher cost of structures in thefurnace. Further, it is even more difficult to prevent heater shapedeformation in the case of the MCZ method in which a magnetic field isapplied. This has, as a result, made it difficult to prevent ununiformtemperature in the raw material melt. For this reason, the presentinventors though out the fact that ununiform temperature in the rawmaterial melt can be prevented by admitting that the heater will deformrather than preventing it and designing the heater with heater shapedeformation in mind in advance such that after deformation the heaterhas a uniform heat generation distribution to the raw material melt,thus perfecting the present invention.

That is, the following two measures are proposed in the presentinvention to ensure that the heater has a uniform heat generationdistribution to the raw material melt in the event of a heater shapedeformation while in use during crystal manufacture.

The first measure consists of having an elliptical, rather thancircular, horizontal cross-section shape of the heat generating portionin expectation of heater shape deformation while in use during crystalmanufacture.

Here, FIGS. 3( a) and 3(b) are schematic views respectively showing thehorizontal cross-sectional shape of the heat generating portion of aconventional heater for manufacturing a crystal before and afterdeformation. As shown in FIG. 3, the conventional circular heatgenerating portion, initially circular, undergoes a deformation while inuse, expanding in diameter after deformation in the direction in whichthe terminal portions 7 b are connected together, diminishing indiameter, conversely, after deformation in the direction in whichportions 90° apart from the terminal portions 7 b are connected togetherand becoming elliptical in shape.

In the present invention, for this reason, the heat generating portionis diminished in diameter in advance in the direction in which thediameter grows larger as a result of heater shape deformation, whereasthe heat generating portion is expanded in diameter in advance in thedirection in which the diameter grows smaller as a result of thedeformation as shown in FIGS. 2( a) and 2(b), thus making available theelliptical heat generating portion (FIG. 2( a)). This allows thehorizontal cross-sectional shape of the heat generating portion of theheater to become circular (FIG. 2( b)) during deformation due to its ownweight and so on while in use, thus providing uniform heat generation tothe raw material melt following deformation.

On the other hand, when the horizontal cross-sectional shape of the heatgenerating portion of the heater is elliptical as in this case, theupper and lower portions of the heater's heat generating portion tradeplaces—one with diminishing diameter and the other with expandingdiameter. Therefore, it is most preferred that the upper and lowerportions be different in diameter. However, such a heater results in acomplex shape of the heat generating portion, thus making itsfabrication difficult. In actuality, therefore, it is most effective todetermine the shape primarily taking into consideration deformation ofthe heat generating slit portions.

It is to be noted that when the horizontal cross-sectional shape of theheat generating portion of the heater is elliptical as described above,it is preferred that, when the longer diameter is D1 and the shorterdiameter is D2, the value of D1/D2 be 1.01 to 1.20. Further, it is morepreferred that the value of D1/D2 be 1.03 to 1.10.

Unless the value of D1/D2 is 1.01 or more, it is nearly impossible toexpect an effect of canceling out the heater's deformed portion. On theother hand, an elliptical shape with the value beyond 1.20 results inhigh machining cost. Also in terms of heater strength, it is preferredthat the value be 1.20 or less.

The second measure consists of imparting an uneven distribution to theelectrical resistance of the heat generating portion in advance inanticipation of heater shape deformation while in use during crystalmanufacture. At this time, electrical resistance of the heat generatingportion is increased in advance in the direction in which the diametergrows larger as a result of heater shape deformation, whereas electricalresistance is reduced in advance in the direction in which the diametergrows smaller as a result of the deformation. This ensures that areasfarther from the raw material melt generate more heat whereas areascloser to the raw material melt generate less heat during deformation,thus providing uniform heat generation to the raw material melt afterdeformation.

Electrical resistance distribution of the heat generating portion can beadjusted, for example, by changing one or more of (1) the thickness ofthe heat generating slit portion (symbol “α” in FIG. 1), (2) the widthof the heat generating slit portion (symbol “β” in FIG. 1) and (3) thelength of the heat generating slit portion (symbol “γ” in FIG. 1).

It is to be noted that if an uneven distribution is imparted to theelectrical resistance of the heat generating portion as described above,it is preferred that when electrical resistance is R1 in the directionin which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and electricalresistance is R2 in the direction in which the diameter grows smaller,the value of R1/R2 be distributed in the range from 1.01 to 1.10.Further, it is more preferred that the value of R2/R1 be distributed inthe range from 1.01 to 1.05.

The reason lies in that the value of R2/R1 below 1.01 will provelimitedly effective whereas changes in thickness and others so as tohave the value beyond 1.10 will involve difficulty in machining and maypresent a problem in terms of heater strength.

On the other hand, a heater may be employed that combines theaforementioned both measures. This allows for fine adjustment to provideuniform heat generation to the raw material melt. That is, thehorizontal cross-sectional shape of the heater's heat generating portionis made elliptical at the same time imparting an uneven distribution tothe electrical resistance. This makes it possible to deal with anydeformation in the heater, allowing for fine adjustment to uniformtemperature distribution. Moreover, this makes it possible to reduce themagnitude of shape deformation of the heater to be machined, as a resultof which favorable results were obtained in terms of heater strength.

As described above, the heater for manufacturing a crystal according tothe present invention is particularly effective for manufacturing acrystal by the MCZ method. The heater for manufacturing a crystalaccording to the present invention can also be employed to manufacturesilicon single crystals.

The heater according to the present invention is used in the MCZ methodbecause the MCZ method is particularly employed for manufacturing largediameter crystals and also because the heater readily deforms as aresult of interaction between current and magnetic field. The heateraccording to the present invention is used to manufacture silicon singlecrystals because the heater size is on the increase due to recentsignificant growth particularly in silicon single crystal diameter.

Further, the present invention provides a crystal manufacturingapparatus furnished with the aforementioned heater for manufacturing acrystal and a crystal manufacturing method for manufacturing a crystalby the Czochralski method using the crystal manufacturing apparatus. Thepresent invention can significantly improve monocrystallization rate bysimply placing the heater having the above properties in a crystalmanufacturing apparatus having a conventional furnace structure,eliminating the need to make design and other changes to the existingapparatus and thereby providing an extremely easy and inexpensive way toconfigure a crystal manufacturing apparatus.

The heater for manufacturing a crystal provided by the present inventionhas a uniform heat generation distribution to the raw material meltafter deformation while in use during crystal manufacture, thusproviding improved dislocation free rate of crystals in single crystalmanufacture and thereby ensuring stable manufacture of high-qualitycrystals. Moreover, the heater keeps the furnace inner structurenon-complex and allows ensuring uniformity in heat generationdistribution to the raw material melt in a relatively inexpensive andreliable manner.

While described more specifically below with reference to examples, thepresent invention is not limited thereto.

EXAMPLE 1

Silicon single crystals were manufactured by the MCZ method in which ahorizontal magnetic field was applied. Raw material—300 kg ofsilicon—was charged into a 32-inch-diameter crucible (800 mm), with12-inch-diameter silicon single crystals (305 mm) pulled. At this time,a heater was used having an elliptical heat generating portion—with thelonger diameter D1 of 925 mm and the shorter diameter D2 (terminal side)of 915 mm (D1/D2=1.01)—and a uniform electrical resistance across theheat generating portion. Crystal manufacture using this heater proceededwith no particular problems, successfully growing crystals to the end.

It is to be noted that dislocation free rate is shown in Table 1 whensilicon single crystals were pulled 20 times under these conditions.

EXAMPLE 2

As with example 1, silicon single crystals were manufactured by the MCZmethod in which a horizontal magnetic field was applied. Rawmaterial—300 kg of silicon—was charged into a 32-inch-diameter crucible(800 mm), with 12-inch-diameter silicon single crystals (305 mm) pulled.At this time, a heater was used having a circular heat generatingportion of 920 mm in diameter, in which when electrical resistance ofthe heat generating slit portions is R1 in the direction (terminal side)in which the diameter grows larger to become the longer diameter as aresult of heater shape deformation while in use during crystalmanufacture and electrical resistance of the heat generating slitportions is R2 in the direction in which the diameter grows smaller tobecome the shorter diameter, R1/R2=1.10. An uneven distribution wasimparted to the electrical resistance of the heat generating slitportions by making the heat generating slit portions constituting theshorter diameter 33 mm in thickness and those portions constituting thelonger diameter 30 mm in thickness. Crystal manufacture using thisheater proceeded with no particular problems, successfully growingcrystals to the end.

It is to be noted that dislocation free rate is shown in Table 1 whensilicon single crystals were pulled 20 times under these conditions.

Comparative Example 1

As with example 1, silicon single crystals were manufactured by the MCZmethod in which a horizontal magnetic field was applied. Rawmaterial—300 kg of silicon—was charged into a 32-inch-diameter crucible(800 mm), with 12-inch-diameter silicon single crystals (305 mm) pulled.At this time, a heater was used having a circular heat generatingportion of 920 mm in diameter (D1/D2=1.00), in which the electricalresistance was uniform across the heat generating portion (R1/R2=1.00).It was confirmed, however, at the time of attachment inside the crystalmanufacturing apparatus at room temperature that the heater had deformedby its own weight to an elliptical shape with the longer diameter of 930mm and the shorter diameter of 910 mm. Crystal manufacture using thisheater led, after manufacturing a certain number of crystals, to surfacesolidification of the raw material melt being spotted in the directionin which the heat generating portion constituted the longer diameter,occasionally leaving no alternative but to stop crystal manufacture.

It is to be noted that dislocation free rate is shown in Table 1 whensilicon single crystals were pulled 20 times under these conditions.

TABLE 1 Comparative Example 1 Example 2 example 1 Dislocation-free 85 8550 rate (%)

As is apparent from Table 1, dislocation-free rate of grown crystals ishigher when crystals were grown using the heater from examples 1 and 2than when crystals were grown using the heater from comparative example1, demonstrating that dislocation-free rate has been significantlyimproved.

It is to be noted that the present invention is not limited to theaforementioned embodiments. The above embodiments are illustrative, andall those having a configuration substantially identical to andproducing a similar effect to the technical concept described in theclaims of the present invention are included in the technical scope ofthe present invention.

For example, while the MCZ method was described in the examples of thepresent invention in which a magnetic field is applied primarily duringpulling of a silicon single crystal, the present invention is notlimited thereto and may be used for the normal CZ method in which nomagnetic field is applied.

Moreover, crystals to be pulled are not limited to silicon, and it isneedless to say that the present invention can be used for growingcompound semiconductors, oxide single crystals and others.

1. A heater for manufacturing a crystal by the Czochralski methodcomprising at least terminal portions supplied with current and a heatgenerating portion by resistance heating, and being arranged so as tosurround a crucible containing a raw material melt, wherein the heaterhas a uniform heat generation distribution to the raw material meltafter a shape of a horizontal cross section of the heater undergoesdeformation while in use during crystal manufacture.
 2. A heater formanufacturing a crystal by the Czochralski method comprising at leastterminal portions supplied with current and a heat generating portion byresistance heating, and being arranged so as to surround a cruciblecontaining a raw material melt, wherein a shape of a horizontal crosssection of the heat generating portion of the heater is an ellipticalshape, and the shape of the horizontal cross section of the heatgenerating portion becomes a circular shape as a result of heater shapedeformation while in use during crystal manufacture.
 3. The heater formanufacturing a crystal according to claim 2, wherein the ellipticalshape of the horizontal cross section of the heat generating portion isachieved by reducing the diameter in advance in the direction in whichthe diameter grows larger as a result of heater shape deformation whilein use during crystal manufacture and by expanding the diameter inadvance in the direction in which the diameter grows smaller.
 4. Theheater for manufacturing a crystal according to claim 3, wherein when,in the elliptical shape of the horizontal cross section of the heatgenerating portion, the longer diameter is D1 and the shorter diameteris D2, the value of D1/D2 is 1.01 to 1.20.
 5. The heater formanufacturing a crystal according to claim 2, wherein when, in theelliptical shape of the horizontal cross section of the heat generatingportion, the longer diameter is D1 and the shorter diameter is D2, thevalue of D1/D2 is 1.01 to 1.20.
 6. A heater for manufacturing a crystalby the Czochralski method comprising at least terminal portions suppliedwith current and a heat generating portion by resistance heating, andbeing arranged so as to surround a crucible containing a raw materialmelt, wherein the heat generating portion of the heater has an unevendistribution of electrical resistance, and wherein the unevendistribution of electrical resistance of the heat generating portion issuch that electrical resistance is increased in advance in the directionin which a diameter of the heater grows larger as a result of heatershape deformation while in use during crystal manufacture, whereaselectrical resistance is reduced in advance in the direction in whichthe diameter grows smaller.
 7. The heater for manufacturing a crystalaccording to claim 6, wherein the uneven distribution of electricalresistance of the heat generating portion is adjusted by changing one ormore of thickness, width, and length of heat generating slit portions.8. The heater for manufacturing a crystal according to claim 7, whereinthe uneven distribution of electrical resistance of the heat generatingportion is such that when electrical resistance is R1 in the directionin which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and electricalresistance is R2 in the direction in which the diameter grows smaller,the value of R1/R2 is 1.01 to 1.10.
 9. The heater for manufacturing acrystal according to claim 8, wherein a shape of a horizontal crosssection of the heat generating portion of the heater is an ellipticalshape, and the shape of the horizontal cross section of the heatgenerating portion becomes a circular shape as a result of heater shapedeformation while in use during crystal manufacture.
 10. The heater formanufacturing a crystal according to claim 6, wherein a shape of ahorizontal cross section of the heat generating portion of the heater isan elliptical shape, and the shape of the horizontal cross section ofthe heat generating portion becomes a circular shape as a result ofheater shape deformation while in use during crystal manufacture andwherein the elliptical shape of the horizontal cross section of the heatgenerating portion is achieved by reducing the diameter in advance inthe direction in which the diameter grows larger as a result of heatershape deformation while in use during crystal manufacture and byexpanding the diameter in advance in the direction in which the diametergrows smaller.
 11. The heater for manufacturing a crystal according toclaim 8, wherein a shape of a horizontal cross section of the heatgenerating portion of the heater is an elliptical shape, and the shapeof the horizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture and wherein when, in the elliptical shape ofthe horizontal cross section of the heat generating portion, the longerdiameter is D1 and the shorter diameter is D2, the value of D1/D2 is1.01 to 1.20.
 12. The heater for manufacturing a crystal according toclaim 8, wherein a shape of a horizontal cross section of the heatgenerating portion of the heater is an elliptical shape, and the shapeof the horizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture, wherein the elliptical shape of thehorizontal cross section of the heat generating portion is achieved byreducing the diameter in advance in the direction in which the diametergrows larger as a result of heater shape deformation while in use duringcrystal manufacture and by expanding the diameter in advance in thedirection in which the diameter grows smaller, and wherein when, in theelliptical shape of the horizontal cross section of the heat generatingportion, the longer diameter is D1 and the shorter diameter is D2, thevalue of D1/D2 is 1.01 to 1.20.
 13. The heater for manufacturing acrystal according to claim 7, wherein a shape of a horizontal crosssection of the heat generating portion of the heater is an ellipticalshape, and the shape of the horizontal cross section of the heatgenerating portion becomes a circular shape as a result of heater shapedeformation while in use during crystal manufacture and wherein theelliptical shape of the horizontal cross section of the heat generatingportion is achieved by reducing the diameter in advance in the directionin which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and by expanding thediameter in advance in the direction in which the diameter growssmaller.
 14. The heater for manufacturing a crystal according to claim7, wherein a shape of a horizontal cross section of the heat generatingportion of the heater is an elliptical shape, and the shape of thehorizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture and wherein when, in the elliptical shape ofthe horizontal cross section of the heat generating portion, the longerdiameter is D1 and the shorter diameter is D2, the value of D1/D2 is1.01 to 1.20.
 15. The heater for manufacturing a crystal according toclaim 7, wherein a shape of a horizontal cross section of the heatgenerating portion of the heater is an elliptical shape, and the shapeof the horizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture, wherein the elliptical shape of thehorizontal cross section of the heat generating portion is achieved byreducing the diameter in advance in the direction in which the diametergrows larger as a result of heater shape deformation while in use duringcrystal manufacture and by expanding the diameter in advance in thedirection in which the diameter grows smaller, and wherein when, in theelliptical shape of the horizontal cross section of the heat generatingportion, the longer diameter is D1 and the shorter diameter is D2, thevalue of D1/D2 is 1.01 to 1.20.
 16. The heater for manufacturing acrystal according to claim 6, wherein the uneven distribution ofelectrical resistance of the heat generating portion is such that whenelectrical resistance is R1 in the direction in which the diameter growslarger as a result of heater shape deformation while in use duringcrystal manufacture and electrical resistance is R2 in the direction inwhich the diameter grows smaller, the value of R1/R2 is 1.01 to 1.10.17. The heater for manufacturing a crystal according to claim 16,wherein a shape of a horizontal cross section of the heat generatingportion of the heater is an elliptical shape, and the shape of thehorizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture.
 18. The heater for manufacturing a crystalaccording to claim 16, wherein a shape of a horizontal cross section ofthe heat generating portion of the heater is an elliptical shape, andthe shape of the horizontal cross section of the heat generating portionbecomes a circular shape as a result of heater shape deformation whilein use during crystal manufacture and wherein the elliptical shape ofthe horizontal cross section of the heat generating portion is achievedby reducing the diameter in advance in the direction in which thediameter grows larger as a result of heater shape deformation while inuse during crystal manufacture and by expanding the diameter in advancein the direction in which the diameter grows smaller.
 19. The heater formanufacturing a crystal according to claim 16, wherein a shape of ahorizontal cross section of the heat generating portion of the heater isan elliptical shape, and the shape of the horizontal cross section ofthe heat generating portion becomes a circular shape as a result ofheater shape deformation while in use during crystal manufacture andwherein when, in the elliptical shape of the horizontal cross section ofthe heat generating portion, the longer diameter is D1 and the shorterdiameter is D2, the value of D1/D2 is 1.01 to 1.20.
 20. The heater formanufacturing a crystal according to claim 16, wherein a shape of ahorizontal cross section of the heat generating portion of the heater isan elliptical shape, and the shape of the horizontal cross section ofthe heat generating portion becomes a circular shape as a result ofheater shape deformation while in use during crystal manufacture,wherein the elliptical shape of the horizontal cross section of the heatgenerating portion is achieved by reducing the diameter in advance inthe direction in which the diameter grows larger as a result of heatershape deformation while in use during crystal manufacture and byexpanding the diameter in advance in the direction in which the diametergrows smaller, and wherein when, in the elliptical shape of thehorizontal cross section of the heat generating portion, the longerdiameter is D1 and the shorter diameter is D2, the value of D1/D2 is1.01 to 1.20.
 21. The heater for manufacturing a crystal according toclaim 6, wherein a shape of a horizontal cross section of the heatgenerating portion of the heater is an elliptical shape, and the shapeof the horizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture.
 22. The heater for manufacturing a crystalaccording to claim 7, wherein a shape of a horizontal cross section ofthe heat generating portion of the heater is an elliptical shape, andthe shape of the horizontal cross section of the heat generating portionbecomes a circular shape as a result of heater shape deformation whilein use during crystal manufacture.
 23. The heater for manufacturing acrystal according to claim 6, wherein a shape of a horizontal crosssection of the heat generating portion of the heater is an ellipticalshape, and the shape of the horizontal cross section of the heatgenerating portion becomes a circular shape as a result of heater shapedeformation while in use during crystal manufacture and wherein theelliptical shape of the horizontal cross section of the heat generatingportion is achieved by reducing the diameter in advance in the directionin which the diameter grows larger as a result of heater shapedeformation while in use during crystal manufacture and by expanding thediameter in advance in the direction in which the diameter growssmaller.
 24. The heater for manufacturing a crystal according to claim6, wherein a shape of a horizontal cross section of the heat generatingportion of the heater is an elliptical shape, and the shape of thehorizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture and wherein when, in the elliptical shape ofthe horizontal cross section of the heat generating portion, the longerdiameter is D1 and the shorter diameter is D2, the value of D1/D2 is1.01 to 1.20.
 25. The heater for manufacturing a crystal according toclaim 6, wherein a shape of a horizontal cross section of the heatgenerating portion of the heater is an elliptical shape, and the shapeof the horizontal cross section of the heat generating portion becomes acircular shape as a result of heater shape deformation while in useduring crystal manufacture, wherein the elliptical shape of thehorizontal cross section of the heat generating portion is achieved byreducing the diameter in advance in the direction in which the diametergrows larger as a result of heater shape deformation while in use duringcrystal manufacture and by expanding the diameter in advance in thedirection in which the diameter grows smaller, and wherein when, in theelliptical shape of the horizontal cross section of the heat generatingportion, the longer diameter is D1 and the shorter diameter is D2, thevalue of D1/D2 is 1.01 to 1.20.